Road construction is an art having its roots in antiquity. Modern road building techniques involve the use of large earth, cement, and asphalt handling vehicles. Despite the many advances in road building machinery, some of the techniques for testing materials in the field remain cumbersome and old fashioned.
One method for testing earth compaction is called the Ottawa sand test, wherein a fine sand is poured from a bottle into a hole from which foundation soil has been removed by the use of a large spoon. The weight of the Ottawa sand that fills the hole is determined by weighing the remaining Ottawa sand in the bottle, and then subtracting that weight from the entire sand and bottle weight. The sand weight that fills the hole is then compared to that of the removed soil. Compaction and moisture calculations can then be made for the foundation soil.
Another road building method involves taking a small sample portion of a large batch of hot asphalt for testing purposes. The batch of hot asphalt is first sampled from the haul unit or sampling device using metal buckets. Then, it is poured on a tray and spread evenly in a pan. Next, a spatula or blade is used to divide the material down the middle vertically and then horizontally, forming a plus sign in the material. Next, two opposing corners of the sample are removed using a scoop and spatula. The remaining asphalt is then used as a test sample.
This technique does not provide an accurate sample, because the material tends to segregate and cool down when handled in this manner. For testing purposes, the sample then requires reheating, resulting in lost time and the inconvenience of additional procedural steps. It has occurred to some that splitter-type machines might be used to quarter asphalt, but this is not possible, owing to the tacky nature of the asphalt.
The present invention has developed a machine for obtaining a hot mix asphalt sample that will not segregate or require reheating. The machine of this invention can quickly reduce even sticky asphalt to the correct size for testing.
The inventive apparatus for volumetrically testing these materials must conform to the procedures and specifications outlined and defined in the manual for the American Association of State Highway and Transportation Officials, or AASHTO (444 North Capitol Street, N.W., Suite 249, Washington, D.C. 20001).